| 摘要 |
An improved automatic transmission has a reverse gear piston which can be engaged as a transmission brake. The piston is movable in a first direction and has a surface. A hydraulic system supplies transmission fluid to a space between the surface and the housing to engage the piston and removes the hydraulic fluid from the space to disengage the piston thereby releasing the transmission brake. In one embodiment, the hydraulic means has a passageway with the first cross-sectional area through the housing and a second cross-sectional area larger than the first cross-sectional area in the housing that is exposed to the space thereby reducing friction between the fluid and the second cross-section which reduces the release time of the fluid from the space. In another embodiment, the transmission has an apparatus for adjusting the cross-sectional area of the passageway through the housing. In another embodiment, an apparatus for bleeding air from the fluid in either the space or the passageway is added to reduce air compression/decompression problems. In yet another embodiment, an explosion proof bellhousing around the flexplate area protects the engine, transmission, passenger compartment, and roadway from flying debris in case of a failing flexplate.
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